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The Sunbeam Crusader, originally known as the Sunbeam 150 hp, Sunbeam 110 hp or Sunbeam 100 hp (variations on the engine may also have been referred to as Sunbeam 120 hp or Sunbeam 135 hp), was an early British, side-valve, water-cooled, 90 degree, V-8 aero engine first marketed in 1913.

First run in December 1912, the first aero-engine from Louis Coatalen was the 110 hp, a water-cooled V-8 with side-valve cylinders of 80mm (3.15 in) bore and 150mm (5.9 in) stroke. The later versions of the engine, which had 90mm (3.5 in) bore cylinders, were known as the 150 hp until the Sunbeam naming system labelled it the Crusader in 1917. The 80mm bore versions were produced in limited numbers, mostly for civil use, but later 90mm bore engines had limited success in civil applications, with more than 226 built for military aircraft.

Production examples were rated at 150 hp (112 kW) at 2,000 rpm, had a Bore of 90mm (3.5 in), stroke of 150mm (5.9 in), two valves per cylinder, and weighed 480 lb (220 kg) dry. The engine was used in a wide variety of British military aircraft during the first years of World War I, most notably the Short 827 seaplane for which six of the original versions were ordered followed by 107 of the more powerful type.

Produced from 1912 to July 1916, over 228 were built.

Further development of the Crusader resulted in the Sunbeam Zulu and V-12 Sunbeam Mohawk and Sunbeam Gurkha.

200 hpInitial version of the V-12 Mohawk built with 80mm (3.15in) bore, developing 200 hp (149 kW). The Admiralty required more powerful engines than the Crusader, so Coatalen designed the Sunbeam 225 hp (168 kW) as a 60 degree V-12 using blocks of three cylinders instead of the twin-cylinder blocks of the Crusader.

225 hpProduction versions built with 90mm (3.5in) bore, rated at 225 hp (168 kW). Short seaplanes using this engine were often called “225s”. During 1917 this engine was re-named as the Sunbeam Mohawk.

CrusaderThe name Crusader was applied to the engine in 1917 after production had ceased, and officially referred only to the later '150hp' version.

ZuluOutwardly dentical to the Crusader, the Zulu was developed during 1915, the bore was increased from 90 mm to 100 mm and the reduction gear ratio was changed to 1.86:1, allowing the engine to develop 160 hp (119 kW) at 2000 rpm. 75 Zulus were built.